Pseudorandom, iterative method and apparatus for automatically creating addresses

Abstract

A pseudorandom, iterative method and apparatus for automatically creating an address for each remote unit of a data communication network comprising a plurality of remote units, such as the seat electronic units (17) of a passenger aircraft, and a central unit, such as a central transmitter/receiver unit (13). The formats of the message frames that control the flow of data between the central unit and the plurality of remote units includes a synchronization word, a command word, and a series of data word segments. The number of data word segments is equal to or greater than the number of remote units. The pseudorandom, iterative method and apparatus assigns addresses such that one and only one remote unit is associated with a data word segment position. First, the central unit transmits an ADDRESS ASSIGN PHASE 1 command to each remote unit. In response, each remote unit randomly selects a data word segment position and replies to the central unit in the selected position. Next, the central unit transmits an ADDRESS ASSIGN PHASE 2 command. All of the remote units that replied in the first data word segment position that contained a reply respond to the ADDRESS ASSIGN PHASE 2 command. All other remote units are locked out. The responding remote units randomly select another data word segment position and respond to the central unit in the selected position. The central unit retransmits an ADDRESS ASSIGN PHASE 2 command. All of the remote units that responded, in the first data word segment position that contained a response, reply to the ADDRESS ASSIGN PHASE 2 retransmission. All of the remote units that responded in other positions are locked out. The transmission of ADDRESS ASSIGN PHASE 2 commands is repeated for N cycles. Alternatively, the process can be repeated until the remote unit response is found to be error-free, which indicates that the response was produced by a single remote unit. In either case, after completion of the ADDRESS ASSIGN PHASE 2 command transmissions, the central unit transmits an ADDRESS ASSIGN PHASE 3 command, which instructs the single responding remote unit to assign itself a unique address and, then, lock itself out of the iterative process. Thereafter, the entire process is repeated until no further responses are received to an ADDRESS ASSIGN PHASE 1 command.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A pseudorandom, iterative method of assigning addresses to a plurality of remote units coupled to a central unit via a communication medium for communication via messages comprising frames that include a series of data word segment positions, said method comprising the steps of: transmitting from said central unit to said remote units a first message;   transmitting from said remote units to said central unit a response to said first message, said response being randomly located in one of said data word segment positions;   transmitting from said central unit to said remote units a second message, said second message containing data that identifies one and only one data word segment position that contained a remote unit response to said first message;   transmitting only from said remote units that responded to said first message in said one and only one data word segment position identified in said second message a response to said second message, said response being randomly located in one of said data word segment positions;   sequentially repeating a number of times the transmission of said second message from said central unit to said remote unit, each of said repeated second messages containing data that identifies one and only one data word segment position that contained a remote unit response to the immediately preceding second message;   sequentially transmitting only from said remote units that responded to a second message in the data word segment position identified in a retransmitted second message a response to said second messages, said responses being randomly located in one of said data word segment positions;   after said second message has been repeated said predetermined number of times, transmitting from said central unit to said remote units a third message, said third message containing data that identifies one and only one data word segment position that contained a response to the last one of said repeated second messages and remote unit address data;   transmitting only from the remote unit that responded to said last one of said repeated second messages a response to said third message if said one and only one data word segment position identified in said third message corresponds to the data word segment position in which said remote unit responded to said last one of said repeated second messages; and   repeating said steps until none of said remote units responds to a first message.   
     
     
       2. A pseudorandom, iterative method of assigning addresses as claimed in claim 1, wherein: said message frames also include a command word segment;   said first message includes a first command word, said second message includes a second command word, and said third message includes a third command word; and   the response by said remote units is dependent upon the nature of said first, second, and third command words.   
     
     
       3. A pseudorandom, iterative method of assigning addresses as claimed in claim 2, wherein said predetermined number of repetitions of said second message is fixed. 
     
     
       4. A pseudorandom, iterative method of assigning addresses as claimed in claim 2, wherein said predetermined number of repetitions of said second message is determined by said central unit evaluating the responses to said second messages received from said remote units and terminating said repetitions when said central unit receives a response from a single remote unit in one of said data word segment positions. 
     
     
       5. A pseudorandom, iterative method of assigning addresses as claimed in claims 1, 2, 3 or 4, including the step of locking out said remote units from responding to said second messages transmitted by said central unit when the one and only one data word segment position identified in a second message does not correspond to the data word segment position in which a remote unit responded to the immediately preceding second message. 
     
     
       6. A pseudorandom, iterative method of assigning addresses as claimed in claim 1, wherein said predetermined number of repetitions of said second message is fixed. 
     
     
       7. A pseudorandom, iterative method of assigning addresses as claimed in claim 1, wherein said predetermined number of repetitions of said second message is determined by said central unit evaluating the responses to said second messages received from said remote units and terminating said repetitions when said central unit receives a response from a single remote unit in one of said data word segment positions. 
     
     
       8. A pseudorandom, iterative method of assigning addresses as claimed in claims 6 or 7, including the step of locking out said remote units from responding to said second messages transmitted by said central unit when the one and only one data word segment position identified in a second message does not correspond to the data word segment position in which a remote unit responded to the immediately preceding second message. 
     
     
       9. In a network comprising a plurality of remote units coupled to a central unit via a communication medium for communication therebetween via messages comprising frames that include a series of data word segment positions, the improvement comprising apparatus for controlling the assigning addresses to said remote units by causing: said central unit to transmit a first message to said remote units;   said remote units to transmit to said central unit a response to said first message, said responses being randomly located in one of said data word segment positions;   said central unit to transmit to said remote units a second message, said second message containing data that identifies one and only one data word segment position that contains a remote unit response to said first message;   only said remote units that responded to said first message in said one and only one data word segment position identified in said second message to transmit to said central unit a response to said second message, said responses being randomly located in one of said data word segment positions;   said central unit to transmit said second message a predetermined number of times to said remote units, each of said repeated second messages containing data that identifies one and only one of said data word segment positions that contained a response to the immediately preceding second message;   only said remote units that responded to a second message in the data word segment position identified in a retransmitted second message to transmit to said central unit a response to said second messages, said responses being randomly located in one of said data word segment positions;   said central unit to transmit to said remote units after said second message has been repeated said predetermined number of times a third message, said third message containing data that identifies one and only one data word segment position that contained a response to the last one of said repeated second messages and remote unit address data;   said remote unit that responded to said last one of said repeated second messages to transmit a response to said third message if said one and only said data word segment position identified in said third message corresponds to the data word segment position in which said remote unit responded to said last one of said repeated messages; and   said central unit and said remote units to repeat said transmissions until said remote units do not respond to a first message transmitted by said central unit.   
     
     
       10. The improvement claimed in claim 9, wherein: said message frames also include a command word segment;   said first message includes a first command word, said second message includes a second command word, and said third message includes a third command word; and   the response by said remote units is dependent upon the nature of said first, second, and third command words.   
     
     
       11. The improvement claimed in claim 10, wherein said predetermined number of repetitions of said second message is fixed. 
     
     
       12. The improvement claimed in claim 10, wherein said predetermined number of repetitions of said second message is determined by said central unit evaluating the responses to said second messages received from said remote units and terminating said repetitions when said central unit receives a response from a single remote unit in one of said data word segment positions. 
     
     
       13. The improvement claimed in claims 9, 10, 11 or 12, including the step of locking out said remote units from responding to said second messages transmitted by said central unit when the one and only one data word segment position identified in a second message does not correspond to the data word segment position in which a remote unit responded to the immediately preceding second message. 
     
     
       14. The improvement claimed in claim 9, wherein said predetermined number of repetitions of said second message is fixed. 
     
     
       15. The improvement claimed in claim 9, wherein said predetermined number of repetitions of said second message is determined by said central unit evaluating the responses to said second messages received from said remote units and terminating said repetitions when said central unit receives a response from a single remote unit in one of said data word segment positions. 
     
     
       16. The improvement claimed in claims 14 or 15, including the step of locking out said remote units from responding to said second messages transmitted by said central unit when the one and only one data word segment position identified in a second message does not correspond to the data word segment position in which a remote unit responded to the immediately preceding second message.